توسعه كامپوزيت هاي نانوساختارAl-Al3V و﴿َAl-(Al3-Al2o3 براي كاربرد در دماي بالا

چكيده انگليسي :

1 Development of Al Al3V and Al Al3V Al2O3 Nanocomposites for High Temperature Applications Seyedeh Zahra Anvari szanvari@ma iut ac ir Date of submission September 21 2014 Department of Materials Engineering Isfahan University of Technology 84156 83111 Iran Supervisor Dr Fatollah Karimzadeh Karimzadeh f@cc iut ac ir Supervisor Prof Mohamad Hossein Enayati ena78@cc iut ac ir Department Graduate Coordinate Program Coordinator Dr K Raeissi Abstract The aim of this study was to produce bulk Al 10 wt Al3 V And Al 10 wt Al3V Al2O3 nanocomposites and to investigate the high temperature properties of samples The structural characteristic of powder particles and consolidated samples were studied by X ray diffraction XRD scaning electron microscopy SEM differential thermal analysis DTA and transmission electron microscopy TEM Mechanical properties and wear behavior of extruded samples at room and high temperature was evaluated In order to study the creep behavior of samples creep tests were performed at 250 350 C The results showed that MA of Al75V25 powder mixture leads to formation of amorphous phase after 40 h After heat treatment of mechanically alloyed powder at 600 C for 1h Al3 V was formed Al3V Al2O3 reinforcements was produced through a mechanochemical reaction of Al and V2O5 In order to produce nanocomposite powders Al3V and Al3 V Al2O3 reinforcements powders were added to the pure Al powders and milled for 5h The prepared nanocomposite powders were consolidated by hot extrusion The average Al grains in the as milled powder was measured to be 40 nm which increased to 50 nm after hot extrusion The result showed that Al 10 wt Al3 V And Al 10 wt Al3V Al2O3 nanocomposites have tensile strength of 209 and 226 MPa repectively In addition mechanical properties at high temperatures showed no drastical decrease up to 300 C The creep test showed significant curvature in plots of the minimum creep rate vs stress leading to high values for the apparent stress exponent and the apparent activation energy for creep By introducing a threshold stress into the analysis it was demonstrated that the true stress exponent n was close to 5 which suggests that the creep is controlled by a dislocation climb process The results of wear test showed a lower wear rate for nanocomposies in contrast to the nanostructure pure Al Dominate wear mechanism of nanocomposites was recognized to be formation of mechanically mixed layer MML on the worn surfaces Comparison of wear behavior of the Al 10 wt Al3V and Al 10 wt Al3 V Al2O3 samples showed that Al 10 wt Al3V sample at different temperatures and for different loads has less wear rate than the Al 10 wt Al3V Al2O3 sample due to the weaker bond strength between Al2O3 particles and aluminum matrix Keywords Aluminium matrix nanocomposite Mechanical alloying Hot extrusion Creep Wear

انوري،زهرا

توسعه كامپوزيت هاي نانوساختارAl-Al3V و﴿َAl-(Al3-Al2o3 براي كاربرد در دماي بالا